/*
 * Copyright (c) 2013 Grzegorz Kostka (kostka.grzegorz@gmail.com)
 *
 *
 * HelenOS:
 * Copyright (c) 2012 Martin Sucha
 * Copyright (c) 2012 Frantisek Princ
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup lwext4
 * @{
 */
/**
 * @file  ext4_ialloc.c
 * @brief Inode allocation procedures.
 */

#include <ext4_config.h>
#include <ext4_types.h>
#include <ext4_misc.h>
#include <ext4_errno.h>
#include <ext4_debug.h>

#include <ext4_trans.h>
#include <ext4_ialloc.h>
#include <ext4_super.h>
#include <ext4_crc32.h>
#include <ext4_fs.h>
#include <ext4_blockdev.h>
#include <ext4_block_group.h>
#include <ext4_bitmap.h>

/**@brief  Convert i-node number to relative index in block group.
 * @param sb    Superblock
 * @param inode I-node number to be converted
 * @return Index of the i-node in the block group
 */
static uint32_t ext4_ialloc_inode_to_bgidx(struct ext4_sblock *sb,
                                           uint32_t inode) {
    uint32_t inodes_per_group = ext4_get32(sb, inodes_per_group);
    return (inode - 1) % inodes_per_group;
}

/**@brief Convert relative index of i-node to absolute i-node number.
 * @param sb    Superblock
 * @param index Index to be converted
 * @return Absolute number of the i-node
 *
 */
static uint32_t ext4_ialloc_bgidx_to_inode(struct ext4_sblock *sb,
                                           uint32_t index, uint32_t bgid) {
    uint32_t inodes_per_group = ext4_get32(sb, inodes_per_group);
    return bgid * inodes_per_group + (index + 1);
}

/**@brief Compute block group number from the i-node number.
 * @param sb    Superblock
 * @param inode I-node number to be found the block group for
 * @return Block group number computed from i-node number
 */
static uint32_t ext4_ialloc_get_bgid_of_inode(struct ext4_sblock *sb,
                                              uint32_t inode) {
    uint32_t inodes_per_group = ext4_get32(sb, inodes_per_group);
    return (inode - 1) / inodes_per_group;
}

#if CONFIG_META_CSUM_ENABLE
static uint32_t ext4_ialloc_bitmap_csum(struct ext4_sblock *sb, void *bitmap) {
    uint32_t csum = 0;
    if (ext4_sb_feature_ro_com(sb, EXT4_FRO_COM_METADATA_CSUM)) {
        uint32_t inodes_per_group = ext4_get32(sb, inodes_per_group);

        /* First calculate crc32 checksum against fs uuid */
        csum = ext4_crc32c(EXT4_CRC32_INIT, sb->uuid, sizeof(sb->uuid));
        /* Then calculate crc32 checksum against inode bitmap */
        csum = ext4_crc32c(csum, bitmap, (inodes_per_group + 7) / 8);
    }
    return csum;
}
#else
#define ext4_ialloc_bitmap_csum(...) 0
#endif

void ext4_ialloc_set_bitmap_csum(struct ext4_sblock *sb, struct ext4_bgroup *bg,
                                 void *bitmap __unused) {
    int desc_size = ext4_sb_get_desc_size(sb);
    uint32_t csum = ext4_ialloc_bitmap_csum(sb, bitmap);
    uint16_t lo_csum = to_le16(csum & 0xFFFF), hi_csum = to_le16(csum >> 16);

    if (!ext4_sb_feature_ro_com(sb, EXT4_FRO_COM_METADATA_CSUM))
        return;

    /* See if we need to assign a 32bit checksum */
    bg->inode_bitmap_csum_lo = lo_csum;
    if (desc_size == EXT4_MAX_BLOCK_GROUP_DESCRIPTOR_SIZE)
        bg->inode_bitmap_csum_hi = hi_csum;
}

#if CONFIG_META_CSUM_ENABLE
static bool ext4_ialloc_verify_bitmap_csum(struct ext4_sblock *sb,
                                           struct ext4_bgroup *bg,
                                           void *bitmap __unused) {

    int desc_size = ext4_sb_get_desc_size(sb);
    uint32_t csum = ext4_ialloc_bitmap_csum(sb, bitmap);
    uint16_t lo_csum = to_le16(csum & 0xFFFF), hi_csum = to_le16(csum >> 16);

    if (!ext4_sb_feature_ro_com(sb, EXT4_FRO_COM_METADATA_CSUM))
        return true;

    if (bg->inode_bitmap_csum_lo != lo_csum)
        return false;

    if (desc_size == EXT4_MAX_BLOCK_GROUP_DESCRIPTOR_SIZE)
        if (bg->inode_bitmap_csum_hi != hi_csum)
            return false;

    return true;
}
#else
#define ext4_ialloc_verify_bitmap_csum(...) true
#endif

int ext4_ialloc_free_inode(struct ext4_fs *fs, uint32_t index, bool is_dir) {
    struct ext4_sblock *sb = &fs->sb;

    /* Compute index of block group and load it */
    uint32_t block_group = ext4_ialloc_get_bgid_of_inode(sb, index);

    struct ext4_block_group_ref bg_ref;
    int rc = ext4_fs_get_block_group_ref(fs, block_group, &bg_ref);
    if (rc != EOK)
        return rc;

    struct ext4_bgroup *bg = bg_ref.block_group;

    /* Load i-node bitmap */
    ext4_fsblk_t bitmap_block_addr = ext4_bg_get_inode_bitmap(bg, sb);

    struct ext4_block b;
    rc = ext4_trans_block_get(fs->bdev, &b, bitmap_block_addr);
    if (rc != EOK)
        return rc;

    if (!ext4_ialloc_verify_bitmap_csum(sb, bg, b.data)) {
        ext4_dbg(DEBUG_IALLOC,
                 DBG_WARN "Bitmap checksum failed."
                          "Group: %" PRIu32 "\n",
                 bg_ref.index);
    }

    /* Free i-node in the bitmap */
    uint32_t index_in_group = ext4_ialloc_inode_to_bgidx(sb, index);
    ext4_bmap_bit_clr(b.data, index_in_group);
    ext4_ialloc_set_bitmap_csum(sb, bg, b.data);
    ext4_trans_set_block_dirty(b.buf);

    /* Put back the block with bitmap */
    rc = ext4_block_set(fs->bdev, &b);
    if (rc != EOK) {
        /* Error in saving bitmap */
        ext4_fs_put_block_group_ref(&bg_ref);
        return rc;
    }

    /* If released i-node is a directory, decrement used directories count
     */
    if (is_dir) {
        uint32_t bg_used_dirs = ext4_bg_get_used_dirs_count(bg, sb);
        bg_used_dirs--;
        ext4_bg_set_used_dirs_count(bg, sb, bg_used_dirs);
    }

    /* Update block group free inodes count */
    uint32_t free_inodes = ext4_bg_get_free_inodes_count(bg, sb);
    free_inodes++;
    ext4_bg_set_free_inodes_count(bg, sb, free_inodes);

    bg_ref.dirty = true;

    /* Put back the modified block group */
    rc = ext4_fs_put_block_group_ref(&bg_ref);
    if (rc != EOK)
        return rc;

    /* Update superblock free inodes count */
    ext4_set32(sb, free_inodes_count, ext4_get32(sb, free_inodes_count) + 1);

    return EOK;
}

int ext4_ialloc_alloc_inode(struct ext4_fs *fs, uint32_t *idx, bool is_dir) {
    struct ext4_sblock *sb = &fs->sb;

    uint32_t bgid = fs->last_inode_bg_id;
    uint32_t bg_count = ext4_block_group_cnt(sb);
    uint32_t sb_free_inodes = ext4_get32(sb, free_inodes_count);
    bool rewind = false;

    /* Try to find free i-node in all block groups */
    while (bgid <= bg_count) {

        if (bgid == bg_count) {
            if (rewind)
                break;
            bg_count = fs->last_inode_bg_id;
            bgid = 0;
            rewind = true;
            continue;
        }

        /* Load block group to check */
        struct ext4_block_group_ref bg_ref;
        int rc = ext4_fs_get_block_group_ref(fs, bgid, &bg_ref);
        if (rc != EOK)
            return rc;

        struct ext4_bgroup *bg = bg_ref.block_group;

        /* Read necessary values for algorithm */
        uint32_t free_inodes = ext4_bg_get_free_inodes_count(bg, sb);
        uint32_t used_dirs = ext4_bg_get_used_dirs_count(bg, sb);

        /* Check if this block group is good candidate for allocation */
        if (free_inodes > 0) {
            /* Load block with bitmap */
            ext4_fsblk_t bmp_blk_add = ext4_bg_get_inode_bitmap(bg, sb);

            struct ext4_block b;
            rc = ext4_trans_block_get(fs->bdev, &b, bmp_blk_add);
            if (rc != EOK) {
                ext4_fs_put_block_group_ref(&bg_ref);
                return rc;
            }

            if (!ext4_ialloc_verify_bitmap_csum(sb, bg, b.data)) {
                ext4_dbg(DEBUG_IALLOC,
                         DBG_WARN "Bitmap checksum failed."
                                  "Group: %" PRIu32 "\n",
                         bg_ref.index);
            }

            /* Try to allocate i-node in the bitmap */
            uint32_t inodes_in_bg;
            uint32_t idx_in_bg;

            inodes_in_bg = ext4_inodes_in_group_cnt(sb, bgid);
            rc = ext4_bmap_bit_find_clr(b.data, 0, inodes_in_bg, &idx_in_bg);
            /* Block group has not any free i-node */
            if (rc == ENOSPC) {
                rc = ext4_block_set(fs->bdev, &b);
                if (rc != EOK) {
                    ext4_fs_put_block_group_ref(&bg_ref);
                    return rc;
                }

                rc = ext4_fs_put_block_group_ref(&bg_ref);
                if (rc != EOK)
                    return rc;

                continue;
            }

            ext4_bmap_bit_set(b.data, idx_in_bg);

            /* Free i-node found, save the bitmap */
            ext4_ialloc_set_bitmap_csum(sb, bg, b.data);
            ext4_trans_set_block_dirty(b.buf);

            ext4_block_set(fs->bdev, &b);
            if (rc != EOK) {
                ext4_fs_put_block_group_ref(&bg_ref);
                return rc;
            }

            /* Modify filesystem counters */
            free_inodes--;
            ext4_bg_set_free_inodes_count(bg, sb, free_inodes);

            /* Increment used directories counter */
            if (is_dir) {
                used_dirs++;
                ext4_bg_set_used_dirs_count(bg, sb, used_dirs);
            }

            /* Decrease unused inodes count */
            uint32_t unused = ext4_bg_get_itable_unused(bg, sb);

            uint32_t free = inodes_in_bg - unused;

            if (idx_in_bg >= free) {
                unused = inodes_in_bg - (idx_in_bg + 1);
                ext4_bg_set_itable_unused(bg, sb, unused);
            }

            /* Save modified block group */
            bg_ref.dirty = true;

            rc = ext4_fs_put_block_group_ref(&bg_ref);
            if (rc != EOK)
                return rc;

            /* Update superblock */
            sb_free_inodes--;
            ext4_set32(sb, free_inodes_count, sb_free_inodes);

            /* Compute the absolute i-nodex number */
            *idx = ext4_ialloc_bgidx_to_inode(sb, idx_in_bg, bgid);

            fs->last_inode_bg_id = bgid;

            return EOK;
        }

        /* Block group not modified, put it and jump to the next block
         * group */
        ext4_fs_put_block_group_ref(&bg_ref);
        if (rc != EOK)
            return rc;

        ++bgid;
    }

    return ENOSPC;
}

/**
 * @}
 */
